package com.hmdp.utils;

import cn.hutool.core.lang.UUID;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.data.redis.support.collections.DefaultRedisList;

import javax.annotation.Resource;
import java.util.Collections;
import java.util.concurrent.TimeUnit;

public class SimpleRedisLock implements ILock {

    private String name;

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    public SimpleRedisLock(String s, StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    private static final String KEY_PREFIX = "lock:";
    private static final String ID_PREFIX = UUID.randomUUID().toString(true) +"-";
    //提前定义好脚本
    private static  final DefaultRedisScript<Long> UNLOCK_SCRIPT;
    //脚本初始化
    static{
        UNLOCK_SCRIPT = new DefaultRedisScript<>();
        UNLOCK_SCRIPT.setLocation(new ClassPathResource("unlock.lua"));
        UNLOCK_SCRIPT.setResultType(Long.class);
    }

    @Override
    public boolean tryLock(long timeoutSec) {
        // 获取线程的标识id
        String threadId = ID_PREFIX + Thread.currentThread().getId();

        // 获取锁
        Boolean success = stringRedisTemplate.opsForValue()
                .setIfAbsent(KEY_PREFIX + name, threadId, timeoutSec, TimeUnit.SECONDS);
        //(Boolean（包装类）),采用这个方式可以避免装箱和拆箱的过程
        return Boolean.TRUE.equals(success);
    }

    //之前的会出现线程安全问题，现在的不会出现
    //主要原因：现在的代码是一行代码，并行运行。之前的是两行代码，会存在不并行的情况
    @Override
    public void unLock() {
        // 调用lua脚本
        stringRedisTemplate.execute(
                UNLOCK_SCRIPT,
                Collections.singletonList(KEY_PREFIX + name),
                ID_PREFIX + Thread.currentThread().getId());
    }

    /*@Override
    public void unLock() {
        //获取线程标识
        String threadId = ID_PREFIX + Thread.currentThread().getId();
        //获取锁的标识
        String id = stringRedisTemplate.opsForValue().get(KEY_PREFIX + name);
        //判断标识是否一致
        if (threadId.equals(id)) {
            //释放锁
            stringRedisTemplate.delete(KEY_PREFIX + name);
        }
    }*/
}
